CHOLESTEROL INTERACTIONS WITH TETRACOSENOIC ACID PHOSPHOLIPIDS IN MODEL CELL-MEMBRANES - ROLE OF THE DOUBLE-BOND POSITION

The synthesis and thermotropic properties of l,2-di-(9Z)-9-tetracosenoylphosphatidylcholine [Δ9-PC(24:1,24:1), 1], l,2-di-(5Z)-5-tetracosenoylphosphatidylcholine [Δ5-PC(24:1,24:1), 2], and 1,2-di-(15Z)-15-tetracosenoylphosphatidylcholine [Δ15-PC(24:1,24:1), 3] are reported. Liposomes prepared from these phospholipids differ from those of the natural sponge phospholipids, l, 2-di-(5Z,9Z)-5,9-hexacosadienoylphosphatidylcholine (4a) and the corresponding ethanolamine (4b), both of which virtually exclude cholesterol from their bilayers. The behavior of 1 and 2 is similar to that of l, 2-di-(6Z,9Z)-6,9-hexacosadienoylphosphatidylcholine (5), which exhibits a partial molecular interaction with cholesterol. In the case of 3, cholesterol appears to interact with the saturated acyl chain regions of this phospholipid in a manner similar to that of its interaction with DPPC acyl chains. This study delineates the effect of the double-bond location in long fatty acyl chains of phospholipids on their interactions with cholesterol. © 1990, American Chemical Society. All rights reserved.